Removal of Tannic acid and COD from synthetic Tannery wastewater

Abstract

Tanning industries generate tannery wastewater having high amounts of tannic acid and high COD. Tannery wastewater is difficult to treat as it is having low biodegradability. Tannic acids or tannins are recalcitrant molecules that are toxic to a wide range of microorganisms. In this study, synthetic tannery wastewater treatment was performed by Electrocoagulation (EC) process. To extract the polyphenolic components of tannins, aluminum was employed as an anode electrode and stainless-steel as cathode electrode. Analysis of removal efficiencies was done by determining tannic acid concentration and COD. The effects of functional parameters such as current density, pH, and initial concentration of tannic acid were examined on the efficiency of electrocoagulation. At a current density of 30 A/m2 with an initial concentration of tannic acid of 1,000 mg/L, 94% of tannic acid removal and 94.92% of COD removal were observed. While tannic acid removal was fast, at 60 min, COD removal took a long duration of 120 min. The removal efficiency was observed for three various pH;4.11 (initial pH of the sample), 6, and 8. The maximal COD elimination was found to be accomplished at pH 4.11, which was the sample's natural pH, whereas tannic acid removal was better at pH 6 and 8. Experiments with a varying initial concentration of tannic acid at 500 mgl-1, 800 mgl-1, and 1000 mgl-1 showed that as concentration was increased, the removal was difficult. The present study found the EC process effective in reducing COD and tannic acid concentration in synthetic tannery wastewater.